Ototoxicity Monitoring

Ototoxicity Monitoring in Tuberculosis Patients With SHOEBOX Audiometry and Extended High Frequency Testing

Audiology and ENT Clinics, Audiometry, Hearing Health, Humanitarian, Ototoxicity Monitoring, Research

Photo Credit: Vital Strategies

Did you know that March 24 is World Tuberculosis Day? It recognizes the date in 1882 when Dr. Robert Koch announced he had discovered the cause of tuberculosis (TB) and it is intended to raise public awareness that, even today, the disease remains an epidemic that causes the deaths of nearly 1.5 million people each year.

TB is caused by a bacterium that affects the lungs. Symptoms include a cough, fever, night sweats, weight loss. Sounds a little like the flu, doesn’t it? It can remain quite mild for many months which often results in people putting off seeking medical treatment. A major issue with TB, although it is curable in many cases, is that it is highly contagious. The germ is easily passed from person to person through saliva when the infected individual coughs, sneezes, or spits. It would not be uncommon for a single infected individual to transmit the disease to 10-15 people within a year through close contact. And without proper treatment, two-thirds of those with TB could die.

Another alarming statistic? One-third of the world’s population has latent TB. This means that they have been infected, but they are not yet sick. The good news is that they cannot pass along the disease to anyone else during this phase. But, they have a 10% chance of becoming ill in their lifetime and if they have an already compromised immune system (say, for example, if they are HIV positive, have diabetes, or suffer from malnutrition) the risk of becoming ill is much greater.

So – how is it treated? TB can be treated with antibiotics, but unlike other bacterial infections, treatment takes much longer. Antibiotics must be taken for at least six to nine months, although the exact course depends on the age, overall health, form of TB (latent or active), and location of the infection in the patient’s body. Since the year 2000 more than 49 million people have been saved through effective diagnosis and treatment – a treatment that includes 4 antimicrobial drugs that are provided along with strong supervision and support by a healthcare worker or a trained volunteer.

Of concern is that certain strains of tuberculosis bacteria have evolved to become resistant to the drugs typically used to cure the disease. There are various factors at play here. Over time the bacterium can mutate when there are interruptions to the strict course of antibiotic treatment (not completing the full 6-9 month cycle) or through ineffective formulations of the drug (such as low-quality medications, the improper storage of the medications, or even the use of a single drug as treatment). Genetic variations carried by certain individuals can also make certain drug treatment ineffective. Known as multidrug-resistant TB (MDR-TB), this is TB that does not respond to either of the two most effective TB treatment drugs.  Continuing down this trajectory, there is also extensively drug-resistant TB (XDR-TB) which is resistant to even more drugs and is extremely challenging to treat.

One of the known side effects of the typical TB treatments is ototoxicity, which means ‘to cause a toxic reaction to the structures of the inner ear’. Damage caused by these treatments can result in hearing loss, tinnitus (ringing in the ears), or dizziness. Hearing loss can be temporary but it is usually irreversible, and permanent hearing loss or balance disorders caused by these ototoxic drugs can have a very damaging impact on patients. We know that those who suffer from hearing loss can have difficulty communicating, but many do not know that they may also retreat socially, as well as suffer feelings of isolation, frustration, and depression. Furthermore, in younger people, they could fall behind in school while for adults, there are economic implications related to employability.

All that to say, for those who are being treated for tuberculosis, it is also important that they are monitored closely for ototoxicity to their specific course of treatment. There are ways to identify early indicators of ototoxicity that can be addressed through changes in drug dosages or the combinations that are being used to treat each patient.

At SHOEBOX Audiometry, we are very proud of the work that many of our partners are doing to monitor TB patients for ototoxicity. Armed with our clinically validated iPad audiometer, they are performing routine hearing testing in over 30 countries as part of their treatment plans. Because the system performs automated testing, it is now possible for the patients to have a hearing test even if they do not have access to a hearing health professional like an audiologist or ENT specialist. Healthcare workers and even volunteers can be trained to administer the testing. SHOEBOX Audiometry will identify and alert the test administrator to any shift in hearing which could be an indication that adjustments should be considered to that patient’s treatment plan.

We recently announced new enhancements to SHOEBOX Audiometry that provide even greater capabilities for ototoxicity monitory. We have added Extended High Frequency (EHF) testing to the system which provides the ability to detect damage to the inner ear earlier than standard hearing evaluations for certain conditions. This is typically a very specialized test that provides the earliest indication of a physiological change to the inner ear even before any change in hearing becomes apparent to the patient. But because we have added this feature to our automated testing platform, the ability to monitor for ototoxicity has been opened up to a vast new audience.

Because the system is so portable, it is uniquely suited for monitoring in remote locations and low-resource settings. For those who are unable to travel for care due of the risk of infection, and those with limited mobility, SHOEBOX Audiometry can be used to perform Extended High Frequency testing where the patients are – rather than requiring the patients to travel to a testing location.

So, as World Tuberculosis Day approaches, we’d like to take a moment to thank all those tireless workers who are dedicated to the treatment of these individuals. TB continues to be one of the world’s deadliest diseases and although the estimates of new cases each year are decreasing, that decline has been very slow. The World Health Organization’s Global TB Strategy aims to eradicate this disease by 2035. Until then, we will continue to partner with our clients to provide an easy and effective way to continuously monitor patients undergoing existing and new treatments, to help manage the important effects of ototoxicity.